//
//  main.c
//  servert
//
//  Created by 徐志瀚 on 17/11/13.
//  Copyright © 2017年 徐志瀚. All rights reserved.
//

#include<netinet/in.h> // sockaddr_in
#include<sys/types.h>  // socket
#include<sys/socket.h> // socket
#include<stdio.h>    // printf
#include<stdlib.h>   // exit
#include<string.h>   // bzero

#define SERVER_PORT 8000
#define LENGTH_OF_LISTEN_QUEUE 20
#define BUFFER_SIZE 1024
#define FILE_NAME_MAX_SIZE 512

int main(void)
{
    // 声明并初始化一个服务器端的socket地址结构
    struct sockaddr_in server_addr;
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htons(INADDR_ANY);
    server_addr.sin_port = htons(SERVER_PORT);
    
    // 创建socket，若成功，返回socket描述符
    int server_socket_fd = socket(PF_INET, SOCK_STREAM, 0);
    if(server_socket_fd < 0)
    {
        perror("Create Socket Failed:");
        exit(1);
    }
    int opt = 1;
    setsockopt(server_socket_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
    
    // 绑定socket和socket地址结构
    if(-1 == (bind(server_socket_fd, (struct sockaddr*)&server_addr, sizeof(server_addr))))
    {
        perror("Server Bind Failed:");
        exit(1);
    }
    
    // socket监听
    if(-1 == (listen(server_socket_fd, LENGTH_OF_LISTEN_QUEUE)))
    {
        perror("Server Listen Failed:");
        exit(1);
    }
    
    while(1)
    {
        // 定义客户端的socket地址结构
        struct sockaddr_in client_addr;
        socklen_t client_addr_length = sizeof(client_addr);
        
        // 接受连接请求，返回一个新的socket(描述符)，这个新socket用于同连接的客户端通信
        // accept函数会把连接到的客户端信息写到client_addr中
        int new_server_socket_fd = accept(server_socket_fd, (struct sockaddr*)&client_addr, &client_addr_length);
        if(new_server_socket_fd < 0)
        {
            perror("Server Accept Failed:");
            break;
        }
        
        // recv函数接收数据到缓冲区buffer中
        char buffer[BUFFER_SIZE];
        bzero(buffer, BUFFER_SIZE);
        if(recv(new_server_socket_fd, buffer, BUFFER_SIZE, 0) < 0)
        {
            perror("Server Recieve Data Failed:");
            break;
        }
        
        // 然后从buffer(缓冲区)拷贝到file_name中
        char file_name[FILE_NAME_MAX_SIZE+1];
        bzero(file_name, FILE_NAME_MAX_SIZE+1);
        strncpy(file_name, buffer, strlen(buffer)>FILE_NAME_MAX_SIZE?FILE_NAME_MAX_SIZE:strlen(buffer));
        printf("%s\n", file_name);
        
        // 打开文件并读取文件数据
        FILE *fp = fopen(file_name, "r");
        if(NULL == fp)
        {
            printf("File:%s Not Found\n", file_name);
        }
        else
        {
            bzero(buffer, BUFFER_SIZE);
            int length = 0;
            // 每读取一段数据，便将其发送给客户端，循环直到文件读完为止
            while((length = fread(buffer, sizeof(char), BUFFER_SIZE, fp)) > 0)
            {
                if(send(new_server_socket_fd, buffer, length, 0) < 0)
                {
                    printf("Send File:%s Failed./n", file_name);
                    break;
                } 
                bzero(buffer, BUFFER_SIZE); 
            } 
            
            // 关闭文件 
            fclose(fp); 
            printf("File:%s Transfer Successful!\n", file_name); 
        } 
        // 关闭与客户端的连接 
        close(new_server_socket_fd); 
    } 
    // 关闭监听用的socket 
    close(server_socket_fd); 
    return 0; 
}